Investigations will continue on the purification and characterization of renal and extrarenal erythrogenin (a factor that interacts with a plasma protein to produce erythropoietin-Ep). Erythrogenin extracted from renal and hepatic lysosomes will be analyzed for purity in a polyacrylamide gel electrophoresis sequence utilizing isoelectric focusing methodology followed by studies of eletrophoretic mobility and sedimentation properties. The ability of separated parenchymal and Kupffer cells from livers of hypoxic nephrectomized rats to produce Ep will be tested in the in vitro plasma clot system. Efforts will be made to purify the plasma factor, with which erythrogenin interacts to produce Ep, by ammonium and polyethylene glycol fractionation procedures. Additional purification will be attempted using preparative gel electrophoresis. Partial purification of the leukocytosis-inducing factor (LIF) will be attempted utilizing polyethylene glycol fractionation and ion-exchange chromatography. Sepharose affinity chromatography and disc gel electrophoresis will be employed to obtain more highly purified LIF. Attempts are being made to purify an anti-LIF evoked in rabbits by injections of rat LIF. The influence of this antiserum on WBC release in 3H-Tdr prelabeled rats will be examined. Such studies should aid in determining whether suppression of leukocyte release alters WBC proliferation and maturation. BIBLIOGRAPHIC REFERENCES: Mechanisms underlying the suppression of erythropoiesis by hyperoxia. S.M. Kaplan, S.J. Piliero and A.S. Gordon. Fed. Proc. 35:251, 1976, abstract. Induced alteration of relative proportions of adult hamster hemoglobins. T. Boussios, J.F. Bertles, M. Kamiyama and A.S. Gordon. Clin. Res. 24:435a, l976, abstract.